1. Field of the Invention
The present invention pertains to oleaginous alkyl group-substituted silicone gels, processes for their preparation, and use thereof.
2. Background Art
Organopolysiloxanes have been used in numerous cosmetic applications for many years. In some of these applications, for example, organopolysiloxanes such as silicone fluids have been employed, either in their native form as oleaginous carriers for other cosmetic ingredients, or in the form of oil-in-water emulsions. In many of the latter cases, a surfactant is necessary in order to keep the silicone fluid in stable suspension or dispersion. Somewhat more recently, numerous cosmetic formulations have employed creams or pastes which include organopolysiloxane gels containing volatile organosiloxanes.
U.S. Pat. No. 5,654,362 discloses silicone gels prepared by reacting a linear, Si—H functional polysiloxane with an α,ω-diene, for example 1,5-hexadiene, in the presence of a platinum hydrosilylation catalyst and a low molecular weight silicone oil. The reaction is continued until a gel is formed following which the silicone gel may be crumbled into a powder, or by addition of further silicone oil, may form a silicone paste. The products are employed to thicken hydrophobic liquids such as silicone oils to a gel-like consistency. A variety of cosmetic products such as an antiperspirants, deodorants, skin creams, etc., are disclosed. The use of flammable diene hydrocarbons in the preparation is a disadvantage. Moreover, creams formed from solid powders are said not to provide acceptable properties, as indicated by U.S. Pat. No. 4,980,167, wherein such formulations are said to suffer from lack of lubricity. Similar products prepared from α,ω-dienes and polyether-functional siloxanes are disclosed in U.S. Pat. No. 5,136,068. However, preparation of water-in-oil emulsions from these compositions still requires use of a separate emulsifying surfactant.
U.S. Pat. No. 4,987,169 discloses preparation of linear and lightly crosslinked organosiloxanes in the presence of silicone oils to form soft powdery or soft, translucent solid particles. The crosslinked organosiloxanes are preferably prepared employing Si—H and vinyl-functional linear organopolysiloxanes, crosslinked through the aid of a hydrosilylation catalyst. Because of the limited crosslinking of the crosslinked organosiloxanes, the amount of the latter necessary to produce the solid product is high, for example 30 to 50% by weight. The product is thus relatively expensive. The soft powders may be used as thickeners in solubilizing additional silicone oil to form greasy compositions stated to be useful in cosmetics and lubricants. The deficiencies of the '169 patent are attested to in U.S. Pat. No. 5,760,116, which discloses products prepared in two stages, in a first step, preparing a highly crosslinked gel from an Si—H functional organopolysiloxane resin in the presence of a minor amount of low viscosity organopolysiloxane, and in a second step, adding further organopolysiloxane oil into the gel under high shear to produce a clear, highly viscous liquid. The disadvantage of two stage production is clear.
U.S. Pat. No. 5,859,069 discloses a gelatinous external skin treatment composition prepared from an organopolysiloxane elastomer powder having spherical particles with an average particle size of 1.0 to 15.0 μm, a silicone oil, and a polyether-modified silicone. The '069 patent indicates that prior formulations employing silicone resins are unsuitable for such uses, as they leave a filmy feeling on the skin. The polyether-modified, resin-free (linear) silicone is disclosed as being absolutely necessary; and if amounts of less than 1.0% by weight are used, gelation becomes insufficient and the composition becomes unsuitable for use in cosmetics. Gelatinous external skin treatment compositions containing the spherical powder, 5-75% by weight of silicone oil, and 1-20% by weight of polyether-modified silicone are disclosed. Preparation of the elastomer particles is not straightforward, and creams containing solid powders have been viewed as undesirable, as previously discussed.
Polyether-functionalized silicone surfactants are disclosed in U.S. Pat. Nos. 5,412,004 and 5,236,986. In each case, a polyether-functional linear Si—H containing organopolysiloxane is reacted with an α,ω-divinyl organopolysiloxane. A further series of compounds are prepared by cross-linking employing an α,ω-bis(unsaturated) polyoxyalkylene polyether instead of the α,ω-divinylsiloxane. However, gels are not formed, and incorporation of silicone oil into the compositions must be performed using high shear kneading. The products contain a high weight percentage of polyether moieties (ca 15% in the examples). The synthesis must necessarily take place in several steps. The additional step of kneading with silicone oil is disadvantageous. Moreover, the α,ω-bis(unsaturated) polyethers are expensive to prepare.
U.S. Pat. No. 5,811,487 describes low molecular weight siloxane fluids thickened with silicone elastomers prepared by reaction of Si—H functional siloxanes and an α,ω-unsaturated diene hydrocarbon, the Si—H siloxane first having been partially reacted with a monoalkenyl functionalized polyether to provide polyether functionality. The necessity of employing α,ω-dienes is disadvantageous, as previously discussed.
U.S. Pat. No. 5,854,336 discloses a process for preparing cosmetic products which involves feeding a silicone elastomer composition consisting of a silicone rubber and a carrier fluid into a reactor, mixing the composition in the reactor, delivering the composition from the reactor to a high pressure pump, and from there into a device for reducing the particles of rubber into smaller sizes. The device for reducing particle size is preferably a high pressure feed homogenizer, most preferably a sonolator. Use of high pressure pumps and devices such as sonolators increase the expense of the product. Stable emulsions and creams containing water and glycols either cannot be prepared, or are difficult to prepare, due to the incompatibility of the hydrophobic silicone and hydrophilic water/glycols.
EP 0 790 055 A1 discloses compositions containing a partially reticulated elastomeric organopolysiloxane and a fatty component such as a triglyceride for use in skin care or make-up formulas. What is meant by “partially reticulated” is not defined in the specification, which refers to U.S. Pat. No. 5,266,321 for its description of suitable organopolysiloxanes.
Examples of cosmetic formulations employing silicone gels are also disclosed in International PCT Applications WO97/44010; WO98/18438; WO98/00105; WO98/00104; WO98/00103; WO98/00102, and like patents. It can be clearly seen from such patents that the range of formulations includes anti-perspirants, both liquid and solid, facial creams, moisturizers, and other products. It should also be apparent from a review of these references that there are considerable differences between the variety of organosilicone gels. In particular, some of these gels provide an unacceptable oily feeling when such is not desired. Other gels are more difficult to produce, and unnecessarily increase the cost of formulation. It would be desirable to be able to produce gels in a simple fashion from well-recognized readily available, and essentially non-toxic ingredients, to produce a product which avoids the stringiness of other gels, which can be dispersed without the use of extremely high pressure devices such as sonolators and the like, and without extensive high shear kneading, and which may produce cosmetic products devoid of oiliness or filmy sensation when applied to the skin.
Creamy gels prepared by polymerizing vinyl-functional MQ resins, Si—H crosslinker, and unsaturated polyoxyalkylene polyethers is disclosed in U.S. application Ser. No. 09/522,480, filed Mar. 10, 2000. Such gels are ideally suited for forming aqueous creamy gels. Similar compositions with somewhat different compatibility with water and other hydrophilic (hydroxylic) solvents is disclosed in U.S. application Ser. No. 09/317,093, filed May 22, 1999. Both of the foregoing applications are incorporated herein by reference. While the aforementioned creamy gels have a wide variety of uses, they suffer from several drawbacks as well. First, the polyoxyalkylene portion of the molecule, due to its hydrophilic nature, limits the ability to formulate with oleophilic components in some instances. Second, the unsaturated polyoxyalkylene compounds used to prepare the gels tend to be relatively expensive. Third, many of the compositions are strictly limited to gel-like or creamy gel preparations. Finally, the compositions may not provide an ideal feel to the skin when used in cosmetic applications.
It would be desirable to form powders and gel-like products which can be used to broaden the formulation window employed, in particular, by the cosmetics industry.